The Coal Pillar Width Effect of Principal Stress Deflection and Plastic Zone Form of Surrounding Rock Roadway in Deep Excavation

Table 3

The maximum principal stress deflection law of surrounding rock in roadway excavation.

Surrounding rock location	Deflection pattern
Roof	Continuous deflection in the vertical direction, but the degree of deflection is weak.; Degree of deflection angle change: .
Coal pillar	The deflection is in the vertical direction, and the degree of deflection is decreasing.; The degree of deflection from the edge of the coal pillar to the middle of the coal pillar shows “strong-medium-weak” transition.; Degree of deflection angle change: .
Floor	Continuous deflection in the vertical direction, with medium deflection at the position of 1.5 m~2 m under both sides of the floor, and weak deflection at other depth positions and the middle of the floor.; Degree of deflection angle change: both sides of the floor > the middle of the floor.; All deflected in the vertical direction and the degree of deflection did not change significantly.
Coal wall	The degree of deflection from the edge of the coal wall to the deep part of the solid coal shows “strong-medium-weak” transition.; Degree of deflection angle change: .